• International Journal of Automotive Technology
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• 제7권7호
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• pp.847-852
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• 2006

A fitting process carried out in the automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that applies heat in the outer diameter of a gear to a suitable range under the tempering temperature and assembles the gear and the shaft made larger than the inner radius of the gear. Its stress depends on the yield strength of a gear. Press fitting is a method that generally squeezes gear toward that of a shaft at room temperature by a press. Another method heats warmly gear and safely squeezes it toward that of a shaft. A warm shrink fitting process for an automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by the process produced dimensional change in both outer diameter and profile of the gear so that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of a warm shrink fitting process in which design parameters such as contact pressure according to fitting interference between outer diameter of a shaft and inner diameter of a gear, fitting temperature, and profile tolerance of gear are involved. In this study, an closed form equation to predict the contact pressure and fitting load was proposed in order to develop an optimization technique of a warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained from theoretical and finite element analysis and also the expanded amounts of the outer diameters of the gears have a good agreement with the results.

• 한국정밀공학회지
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• 제23권9호
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• pp.54-60
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional changes of gear profile in both radial and circumferential directions. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the gear profile in both radial and circumferential directions are within the limit tolerances used in the field.

• 한국정밀공학회지
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• 제16권8호
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• pp.71-78
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• 1999

The application range of injection molded parts is expanding by the development of engineering plastics with good mechanical properties. Plastic gears are specially used as automotive parts due to an excellent performance in the characteristics of a strength vs. weight, and the study of injection molding process of plastic gear using Nylon66 is performed in this study. Filling, packing and cooling analyses were done by using the simulation software like Moldflow, and a mold was designed by following the simulation results. Pin-point gates with three points were taken to satisfy the design guides like a full-shot, and lower clamping force and uniform shrinkage. Characteristics of shrinkage of molded gear and temperature difference between cavity and core sides of a mold were shown.

• 한국기계가공학회지
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• 제18권12호
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• pp.7-14
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• 2019

A marine turning gear controls the position of the piston-crank mechanism by rotating the flywheel of the marine engine at a low speed, which is the main auxiliary machine that enables the disassembly and maintenance of the engine. In this study, the safety factor for surface durability and tooth bending strength was improved by the design modification of the marine turning gear based on the spur planetary gear. Angular velocity, torque, and efficiency of the turning gear were measured using a reliability evaluation tester, and a multibody dynamics model for analysis corresponding to the test results was developed. Finally, it was confirmed that the design improvements improved the tooth surface damage of the sun gear in the 3^rd reduction stage.

• 한국산업융합학회 논문집
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• 제24권5호
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• pp.589-596
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• 2021

In this study, the optimum gating system was designed, and the two zinc alloy worm gears were manufactured in single process by applying a symmetrical gating system with 2 runners. The SRG ratio is set to 1 : 0.9 : 0.6, and the cross-sectional shapes such as sprue, runner and gate are designed. In order to determine whether the design of the gating system is appropriate, casting analysis was carried out. It takes 4.380 s to charge the casting 100%, 0.55 to 0.6 m/s at the gates and solidification begins after the casting is fully charged. The amount of air entrapment is 2% in the left gear and 6% in the right gear. Hot spots occurred in the center hole of the gear, and pores were found to occur around the upper part of the hole. Therefore, the design of the casting method is suitable for worm gears. CT analysis showed that all parts of worm gear were distributed with fine pores and some coarse pores were distributed around the central hole of worm gear. The yield strength and tensile strength were 220 MPa, 285 MPa, and the elongation rate was 8%. Vickers hardness is 82 HV.

• 한국정밀공학회지
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• 제23권5호
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• pp.37-43
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• 2006

Fitting process carried out in automobile transmission assembly line is classified into three classes; heat fitting, press fitting, and their combined fitting. Heat fitting is a method that heats gear to a suitable range under the tempering temperature and squeezes it toward the outer diameter of shaft. Its stress depends on the yield strength of gear. Press fitting is a method that generally squeezes gear toward that of shaft at room temperature by press. Another method heats warmly gear and safely squeezes it toward that of shaft. Warm shrink fitting process for automobile transmission part is now gradually increased, but the parts (shaft/gear) assembled by this process produced dimensional change in both outer diameter and profile of the gear. So that it may cause noise and vibration between gears. In order to solve these problems, we need an analysis of warm shrink fitting process, in which design parameters are involved; contact pressure according to fitting interference between outer diameter of shaft and inner diameter of gear, fitting temperature, and profile tolerance of gear. In this study, an closed form equation to predict contact pressure and fitting load was proposed in order to develop optimization technique of warm shrink fitting process and verified its reliability through the experimental results measured in the field and FEM, that is, thermal-structural coupled field analysis. Actual loads measured in the field have a good agreement with the results obtained by theoretical and finite element analysis and also the expanded amounts of the outer diameters of the gears have a good agreement with results.

• Tribology and Lubricants
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• 제7권2호
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• pp.67-74
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• 1991

The contact characteristics of gear tooth surface were studied by using the gear test rig of power circulation type. The effect of surface treatment conditions and revolutions on the tooth surface roughness parameters, and the relations between the lubrication conditions and tooth surface conditions, in spur gear sets wear considered. The result show that heat treatment of gear have an important effect upon fatigue strength and tooth surface conditions, and surface asperities undergo a circulating process of creation and destruction because of the influnce of plastic deformation. And surface roughness conditions at the tooth tips accompany a great deal of variation in running-in stage. According to the lubrication analysis and the study the tooth surface have a greater effect on surface demage than lubrication conditions, in mixed-lubrication condition.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.242-247
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• 1998

The conventional closed-die forging processes had been applied to forging of the spur gears. But this type process requires high pressure. The commercial finite element analysis code ANSYS for the stress and elastic deformation of non-axisymmetric die was adopted in this study. In the non-axisymmetric die such as gear forging, maximum stresses were imposed on the tip of the gear tooth. When the stress exceeds yield strength of insert die, many approaches were attemped to prevent the die failure. Good shaped products are forged successfully. This type process could by used as an advanced technique to replace conventional hobbing process of gear.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2003년도 추계학술대회논문집
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• pp.316-323
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• 2003

The gear system is commonly applied in the marine propulsion shafting system using the diesel engine with the power take off/in system and it also is necessary to reduce propeller revolution increasing the propulsion efficiency. The diesel engine has the advantage more than other thermal engines in high thermal efficiency and mobility. But the large vibratory torque which induced by higher combustion pressure is transmitted to these gears. In this paper, the surface durability and bending stress of gear system considering vibratory and transient torque is evaluated by ISO and AGMA regulation. And the influence of these in gear design is investigated with the theoretical analysis and onboard measurement result of torsional vibration.

• Journal of Advanced Marine Engineering and Technology
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• 제39권9호
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• pp.895-902
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• 2015

본 연구에서는 사이클로이드기어시스템 1단, 한 쌍의 평기어시스템, 입력 축, 출력 축, 하우징으로 구성되어 있는 2MW급 풍력발전기용 사이클로이드 피치감속기에 대해 유한요소해석을 통한 안정성평가를 수행하였다. 또한 평기어에 대해서는 ISO 6336에 의한 기어강도해석을 통하여 안정성 여부를 평가하였다. 2MW급 풍력발전기용 사이클로이드 감속기의 고유진동 특성 해석을 수행하였고, 입력축 질량불평형, 출력축 질량불평형, 평기어 치합전달오차, 사이클로이드기어 치합전달오차 등에 발생하는 가진원에 대해 위험속도 분석을 하였다.